The present invention generally relates to test sockets and contactors for testing and burn-in of integrated circuit (IC) devices, and more particularly to spring contact pins used in test sockets and contactors to make circuit connections between an IC device and a test or burn-in circuit board. IC devices will sometimes be referred to herein as simply a “chip.”
To facilitate testing and burn-in, test sockets and contactors have been designed for holding IC chip packages and connecting and disconnecting the chip's I/O contacts to a printed circuit (PC) test board, such as used in an automated chip tester. Such chip holding devices commonly use tiny spring contact pins—whose length is measured in millimeters—to achieve an electrical connection between the chip and PC test board. The spring contact pins have a depressible probe or plunger end at one or both ends of a conductive spring barrel and are provided in densely packed arrays in a thin contact wall of the socket or contactor; they are intended to provide an efficient electrical path between IC chip and test PC test board.
As leadless IC devices, such as BGA, LGA and SGAs, have become smaller and their input/output (I/O) densities larger, the challenge of creating test and burn-in sockets having desired and repeatable performance characteristics has increased. Because of the extremely small dimensions of the test socket's spring contact pins, any slight mechanical friction between the components of the contact pins will have a negative effect on the contact pin's mechanical and electrical performance, and will negatively affect the ability of the contact pins to perform consistently over the life of the contact pins, which are subjected to many thousands of test cycles during the expected life of the contact pins.